Thanks for your reply. I purchased a PTAC unit and nowhere in the owner's manual does it indicate amps required; however, on the plug it has 20Amps so I'm assuming that what it requires. My question is that the circuit breaker is 30 amps, do I need to change it to 20 amps or is the 30amp breaker okay?

How about telling us the make and model?

What do the instructions/manual say? They would indicate the required circuit amperage.

Please describe the plug on your AC unit. If it in fact requires 20 amps and you have a properly wired 30 amp circuit you should be fine but plesae describe the plug and then the receptacle you have

Looking at the NEMA Straight Blade Configurations chart, the receptacle is 6-20R and the plug on the unit is a 6-20P.

the receptacle is 6-20R and the plug on the unit is a 6-20P.
WHY do you have a 30A breaker feeding a 20A receptacle? That was wrong from the start.

Change the breaker to 20A and plug it in.

The amps required by a unit, as recommended by manufacturer, should be size of breaker. If larger the unit will not be protected and if overloaded could cause a fire.

Chuck